@muehlfield@social.tchncs.de Here ya go, they include two different sources so it seems good in terms of addressing potential bias.

One source is left-leaning yet still finds 60% of worldwide billionairs were self made. This number is confirmed by forbes int he same article which tends to be more right-leaning. There are tons of other sources you can use to confirm this as well:

https://www.cnbc.com/2014/10/03/two-thirds-of-billionaires-made-it-themselves.html